1. Field of the Invention
The present invention relates to a curvilinear compound separator apparatus and method for separating multiple immiscible liquids, gases, and rigid particles of varying densities from liquid mixtures that are in motion within a temperature and pressure controlled environment. This unique device and method utilizes the particle kinetic energy within a moving stream and the interaction of these particles within the controlled flow pathway to separate immiscible substances. The principles of particle dynamics (forces of buoyancy, weight, drag, and particle translation with respect to the time within the controlled environment (time dependent motion)) are applied to cause the accelerated movement and separation of immiscible particles.
2. Description of Related Art
It is desired to find an effective way to recover petroleum products from brine. In particular, in the field of crude oil production, it is required to have an accelerated liquid/liquid and liquid/gas extraction to minimize the loss of crude oil and natural gas products. Specifically, this device will be applicable for constant flow, pressurized, and temperature regulated processes to increase the efficiency and recover at least 95% of currently lost marketable products. Current extraction and separation methods include: settlementation, which requires a prolonged period of holding the liquid in a quiescent state for a prolonged time; bed filters and inclined plate separators; membranes and filters; and electrostatic processes. The above processes require large storage facilities, which are extremely expensive and hazardous to operate, such as the electrostatic separation process.
The most common practice used in the industry today is phase extraction within a vessel that maintains liquid in a quiescent state, a practice which utilizes Stokes' Law. Stokes' Law relates the drag on a sphere to its velocity, as it moves in a quiescent liquid.Fd=3π(μudp),                 where μ=fluid viscosityIn order for Stokes' law to strictly apply, the fluid must be quiescent and non-moving, or at best, a “creeping flow” and the particles must be substantially rigid (non-deformable) spheres. In such a situation, there is no separation of liquid from the rear of the rising or falling sphere as it moves, and viscous effects dominate the particle's movement. In defining fluid movement, reference to the Reynolds Number (Re) is made. If the Reynolds rise number Ro is greater than 0.1, the drag force F on the sphere cannot be predicted accurately.             Reynolds      ⁢                           ⁢      Number        =                  du        ⁢                                   ⁢        ρ            μ        ,      Re    >    0.10  where:        ρ=density of continuous liquid phase        μ=continuous liquid viscosity        u=relative velocity        d=particle diameter        
In fluid streams with particles immersed within the fluid, the internal flow dynamics of particles can be expressed, in general, as follows:       u    t    =            gd                                         ⁢        2              ⁢                  (                              ρ            p                    -                      ρ            1                          )                    18        ⁢        μ            where:                ρp=density of carrying liquid        ρ1=density of particle or carried liquidThe equation above will apply to the movement of an oil particle within another liquid, such as water, in a quiescent state. This equation expresses the dynamic force on a sphere of diameter d moving with a speed u through a fluid, such as water, that has a viscosity μ. An oil particle naturally tends to rise due to the buoyant forces being greater than gravity and drag forces, because its density, ρp, is lower than the density, ρ1, of water. The oil particle movement, relative to the continuous fluid can be expressed as a function of Reynolds Number where d is the diameter of the spherical oil particle.        
The aforementioned theory applies to small oil particles in the range of ten to twenty microns in diameter and below, which are the hardest particles to remove. Larger diameter liquid spheres will have higher terminal velocities than that predicted by Stokes' Law due to internal liquid circulation within the spheres in a manner well-known to those skilled in the art. Liquid within larger spheres at the interface between the sphere and the surrounding fluid will tend to move along with the surrounding fluid flow and re-circulate back along the axis of the sphere, thereby reducing drag forces at the boundary interface of the sphere. As the spheres become even larger, they tend to deform into an “inverted teardrop” shape” further reducing the drag forces because of the more aerodynamic shape of the deformed particle. Small oil particles, due to their substantially rigid spheres without appreciable deformation or internal circulation, are therefore the hardest particles to remove.
When the rate of the movement of a mixture within an apparatus exceeds a certain critical value, which is dependent on the physical characteristics of the fluid and the Pathways, the flow of the mixture enters the turbulent region of fluid flow. This turbulence within fluid flow renders Stokes' law inapplicable. A measure of the turbulence within a channel of flowing fluid, such as an oil-water mixture, is given by the Reynolds number (Re) for the channel, defined by the well-known relationship   Re  =      ρ    ⁢                   ⁢    V    ⁢          D      μ      where D is the “hydraulic diameter” of a Pathway (channel) and V is the average velocity of the fluid through the channel. If Re is less than 2,000 for water, the flow is completely laminar and non-turbulent. If Re is greater than 2,000 for water, the flow becomes undefined, and enters into a transition region that has some turbulence and is somewhat non-laminar. The higher the Reynolds numbers, the more turbulent the flow becomes. As the viscosity becomes greater, i.e. oils, Re will be reduced by a factor of the ratio of viscosity of water to viscosity of oil, μ. Therefore, Reynolds number greater than 2,000 for oils will remain laminar.
Technologies used on the market today do not address the inapplicability of Stokes' law to a moving flow of water. Such incomplete solutions to the oil-water separation problem yield less than optimal removal of oil from the oil-water mixture. Other approaches employing various filters and the like have a known tendency to clog and become blocked with sediment and are very costly to operate. Mechanical separating systems use mechanical devices such as centrifuges for primary separation. This kind of system is very costly to maintain and operate. Likewise, an electrostatic system's use of high impressed voltage across plate anodes to cause ionic changes for particle agglomeration requires high energy levels, and is hazardous when vapors occur.
The present application exploits the properties of oil and water as two immiscible liquids of differing density. The methods disclosed are applicable to mixtures of any immiscible liquids of different density (buoyancy). For separating particles of one liquid from another within a fluid mixture, it is required to control the liquid environment to prevent uncontrolled turbulence and Pathway clogging to improve efficiency. The apparatus should depend upon the kinetic fluid energy, thermal gradient, and nucleation to cause separation.
Several devices have been developed which perform solid-liquid, liquid-gas, or liquid-liquid separations to some degree in various applications. U.S. Pat. No. 689,366, issued Dec. 17, 1901 to Newbold et al., shows a device which separates gas from an oil-water mixture, but is not designed to separate oil from water. U.S. Pat. No. 1,970,784, issued Aug. 21, 1934 to J. P. Walker, discloses a device for separating an oil-gas mixture from water at well pressure which uses an uncontrolled whirling action in a cylindrical tank but without laminar flow, relying on gravity to separate the oil-gas mix from water.
U.S. Pat. No. 3,064,410, issued Nov. 20, 1962 to H. H. Wright, shows a separator which uses a plurality of baffles for separating oil well fluids. U.S. Pat. No. 3,399,135, issued Aug. 27, 1968 to Conley, Jr. et al., describes a device for the treatment of sewage having a horizontally oriented tank with a plurality of linear tubes which slope slightly upward in the direction of fluid flow. U.S. Pat. No. 3,813,851, issued Jun. 4, 1974 to T. Eder, teaches a separator having a vertical tank in a parallelepiped shape with internal plates or baffles secured to opposite walls of the tank in a zigzag fashion, with one layer of plates being offset from the next succeeding layer so that liquid flow is split between the two.
U.S. Pat. No. 3,957,656, issued May 18, 1976 to J. L. Castelli, describes a separator for oil-brine separation having a tank with corrugated or sine wave shaped top and bottom plates which are oscillated to accelerate or decelerate horizontal flow to cause oil particles to coalesce. U.S. Pat. No. 4,278,545, issued Jul. 14, 1981 to Batutis et al., shows a similar device with the corrugated plates stacked vertically and parallel to the direction of flow.
U.S. Pat. No. 4,072,481, issued Feb. 7, 1978 to C. C. Laval, Jr., teaches a device which separates fluids to protect a pump having an elongated tube with a shorter, concentric “vortex” tube disposed inside, separation being accomplished by gravity and by uncontrolled swirling around the vortex tube. U.S. Pat. No. 4,732,585, issued Mar. 22, 1988 to B. J. Lerner, discloses a separating device having a plurality of staggered rows of cylinders with partition walls arranged parallel to the direction of fluid flow to prevent diagonal flow through the staggered elements.
U.S. Pat. No. 5,149,344, issued Sep. 22, 1992 to D. H. Macy, shows a two tank apparatus for separating an oil-gas-water mixture in which gases are removed in the first tank, and oil and water are separated in the second, lower level tank, the apparatus having a buoyant valve to control fluid level in the lower tank to keep the tank full in order to avoid sloshing in the tank caused by movement of the tanks, such as movement of the tanks in marine or offshore drilling operations. U.S. Pat. No. 6,187,079, issued Feb. 13, 2001 to P. J. Bridger, addresses the same problem and provides horizontal tanks with anti-foaming media and demisting media, and perforated plates for flow restriction.
U.S. Pat. No. 5,334,239, issued Aug. 2, 1994 to Choe et al., teaches a device for separating gas from liquid under microgravity conditions, such as those encountered in outer space. U.S. Pat. No. 5,500,039, issued Mar. 19, 1996 to Mori et al., describes a liquid gas separator for electric plants (a water-steam mixture), in which the separator has a restricted outlet through a perforated plate or a diverter to lengthen the outflow time and allow more time for separation. U.S. Pat. No. 5,698,102, issued Dec. 16, 1997 to B. M. Khudenko, shows various forms of a lamellar separator for separating a solid-liquid-gas mixture in wastewater or biomass systems.
U.S. Pat. No. 5,827,357, issued Oct. 27, 1998 to R. R. Farion, describes a device for separating drilling fluids (water or diesel fluid with nitrogen and rock cuttings) with a vertical tank having a plurality of vortex tubes centrally located and upper and lower chambers above and below the tubes. Incoming fluid is split between the tubes and enters each tube tangentially, gases exiting the top of the vortex tubes, and liquid and solid matter exiting the bottom of the vortex tubes, where they separate by gravity.
A prior patent issued to one of the present applicants, U.S. Pat. No. 5,266,191, issued Nov. 30, 1993 to Greene et al., teaches an apparatus and method for separating oil from water in such applications as parking lot runoff, etc., which uses a horizontally disposed cylindrical tank with weirs at the inlet and outlet and a serpentine fluid flow path defined by serially joined divider plates.
None of the foregoing patents use a heating element to apply a thermal gradient. The following patents show devices with a heating element.
U.S. Pat. No. 2,751,998, issued Jun. 26, 1956 to C. O. Glasgow, describes a horizontally disposed tank with an inlet, an outlet, and a divider wall disposed therebetween extending down from the top wall of the tank but not all the way to the bottom, dividing the tank into heating and settling chambers. U.S. Pat. No. 2,808,123, issued Oct. 1, 1957 to J. P. Walker teaches a device for recovering hydrocarbon gases which uses well stream liquids in a condenser to cool hydrocarbon gases and return them to the tank.
U.S. Pat. No. 2,863,522, issued Dec. 9, 1958 to J. B. Smith, discloses an oil and gas treater which uses cooling from the release of gases as a heat exchange medium. U.S. Pat. No. 2,942,689, issued Jun. 28, 1960 to Walker et al., teaches a separator in which gases of selected molecular weight are reabsorbed in the denuded oil. U.S. Pat. No. 2,971,604, issued Feb. 14, 1961 to C. Lowery, describes a novel heater for a separation tank, some of the separation occurring before the mixture enters the tank. U.S. Pat. No. 6,171,465, issued Jan. 9, 2001 to B. E. Compton, discloses a desalting device which has a horizontal tube or tank with a vertical divider wall so that incoming fluid flows in and doubles back in order to extend flow time, with vertical baffles having spaced apart perforated regions for separating the flow of oil and water. A heater is applied to the flow after the free water has been removed.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.